The present invention relates to an exposure device and an image forming apparatus.
A conventional image forming apparatus such as a printer, a copier, a facsimile machine, a complex machine or the like is configured to form an image as follows. A surface of a photosensitive drum is uniformly charged by a charging roller. The surface of the photosensitive drum is exposed by an LED (Light Emitting Diode) head as an exposure device so that a latent image is formed on the surface of the photosensitive drum. Then, a toner layer formed on a developing roller adheres to the latent image, and a toner image formed. The toner image is transferred to a recording medium by a transfer roller. The toner remaining on the surface of the photosensitive drum after the transferring is removed by a cleaning device.
A general LED head includes an LED array chip that emits light and a rod lens array that focuses the light on the surface of the photosensitive drum. The LED array chip includes LED chips arranged on an elongated substrate.
On the assembling of the LED head, the substrate (with the LED chips) is mounted to a lens array holder (as a supporting member) holding the rod lens array. More specifically, the substrate is inserted into the lens array holder so that both ends of the substrate in the widthwise direction are placed on contact surfaces formed inside the lens array holder. Then, a base made of metal is placed on the substrate, and a plurality of clamps are attached to the lens array holder so as to force the substrate against the contact surfaces via the base. The clamps protrude outwardly from the lens array holder (see, Japanese Laid-open Patent Publication No. H7-115511).